Following are the steps to push a new image to a registry:

Step 1: The first step is to give a tag to your docker image which is a reference to your docker image ID which conveys the information regarding the image version. If you log in to your docker hub account and search for a standard image of MySQL, HTTP, etc there you notice these tags. To build a customized image you need to write a customized Dockerfile.

docker image tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]

If you do not mention the tag then the default tag is the latest. For example,

docker image tag ubuntu:14.04 XYZ/ubuntu:2.0

Ubuntu is a source image in our docker container 14.04 is the tag to that source image.XYZ in the target image name has to be similar to your docker hub account username and the tag is 2.0.     

Step 2: Now if you try to push the image then it will give an error:

denied: requested access to the resource is denied

The reason is that for pushing the image in your docker hub account first you have to log in.   So the second step is to log in to your docker hub account. To login, the command is      

docker login

  Now write your respective username and password you give while creating a docker hub account.             

Note: If you are a Mac user after pushing your image do not forget to logout because the authentication key is written to a file to remember you as user of that docker hub account in the future if it is your personal device no need to do this.

docker logout

By pushing an image to the DockerHub registry, we can create an instance of an image in which a particular type of software and applications are pre-installed and can be pulled again whenever you want to work on that particular type of image or application and run that kind of virtual machine. In the DockerHub there are millions of images you can also pull the default images which are created by particular organizations for example you can pull the Ubuntu image which is uploaded by Linux, and then install any software or application into that image like curl command, Jenkins, etc and then push that docker image to your docker hub registry. 

Docker Push

Docker push is a command which is used to push the docker images to the docker Private/Public registries. After building the customized docker image you need to push it to the remote registries from where other developers or DevOps engineers can access the image and work on it to push the image you can use the docker push command. It is an important step to perform because if you store it locally others can’t access the image but if it is available remotely others can access it.